As is well known, coal washing machine equipment is completed through water washing and pressure filtration. The principle of this equipment is that there is a pressure of 0.2-0.4Mp in the pressurized filter chamber of the coal washing equipment, and the pressure in the chamber is about 0.32Mp. The water content of the filtered coal cake is between 15% -20%, usually around 20%. The coal content of the upper and lower filtrates is less than 10g/L.

　　The coal slurry from the concentration tank is pumped into 8 coal slurry silos of the pressurized filter through 404 and 407. The water in the coal slurry flows into the filter fan through the filter cloth due to pressure, and finally flows into the main shaft filter tube, forming a lower filtrate. During the rotation of the spindle, the filter fan picks up some coal slurry, and the water in the coal slurry flows into the spindle filter tube due to pressure, forming an upper filtrate. When the spindle is turned to the blowback tube, the blowback pressure is greater than the pressure inside the chamber. After reverse blowing, the coal on the filter fan falls off, and then passes through the filter fan scraper. Basically, most of the coal from the filter fan enters the pressurized filter scraper machine, which sends the coal into the discharge device of the coal washing machine and finally enters the clean coal belt. After passing through the steam water separator, the upper and lower filtrates return to the concentration tank.

　　1. The principle of heavy medium cyclone and classification cyclone is similar, both of which separate bottom flow and overflow through huge centrifugal force.

　　2. Density: In a heavy medium cyclone, the closer the medium density is to the cyclone wall, the higher the density, and the closer it is to the bottom flow port, the higher the density. On the contrary, the closer to the center and overflow port, the lower the density.

　　3. Factors that determine coal quality: ① feed flow rate ② diameter of bottom flow outlet ③ length and taper of cyclone.

　　4. Principle: Similar to a tornado, the large centrifugal force on the outer layer causes a low pressure in the center, which sucks in air from the bottom flow port and spirals in the opposite direction with less dense coal to be discharged from the overflow, while the outer layer of gangue is discharged from the bottom flow due to its high density.

　　5. Zero line: the boundary between overflow spiral and underflow spiral. Within the 0-bit line, it is overflow; Beyond is the bottom flow.